Line data Source code
1 : // Copyright 2013 the V8 project authors. All rights reserved.
2 : // Use of this source code is governed by a BSD-style license that can be
3 : // found in the LICENSE file.
4 :
5 : #ifndef V8_BASE_PLATFORM_MUTEX_H_
6 : #define V8_BASE_PLATFORM_MUTEX_H_
7 :
8 : #include "src/base/base-export.h"
9 : #include "src/base/lazy-instance.h"
10 : #if V8_OS_WIN
11 : #include "src/base/win32-headers.h"
12 : #endif
13 : #include "src/base/logging.h"
14 :
15 : #if V8_OS_POSIX
16 : #include <pthread.h> // NOLINT
17 : #endif
18 :
19 : namespace v8 {
20 : namespace base {
21 :
22 : // ----------------------------------------------------------------------------
23 : // Mutex
24 : //
25 : // This class is a synchronization primitive that can be used to protect shared
26 : // data from being simultaneously accessed by multiple threads. A mutex offers
27 : // exclusive, non-recursive ownership semantics:
28 : // - A calling thread owns a mutex from the time that it successfully calls
29 : // either |Lock()| or |TryLock()| until it calls |Unlock()|.
30 : // - When a thread owns a mutex, all other threads will block (for calls to
31 : // |Lock()|) or receive a |false| return value (for |TryLock()|) if they
32 : // attempt to claim ownership of the mutex.
33 : // A calling thread must not own the mutex prior to calling |Lock()| or
34 : // |TryLock()|. The behavior of a program is undefined if a mutex is destroyed
35 : // while still owned by some thread. The Mutex class is non-copyable.
36 :
37 : class V8_BASE_EXPORT Mutex final {
38 : public:
39 : Mutex();
40 : ~Mutex();
41 :
42 : // Locks the given mutex. If the mutex is currently unlocked, it becomes
43 : // locked and owned by the calling thread, and immediately. If the mutex
44 : // is already locked by another thread, suspends the calling thread until
45 : // the mutex is unlocked.
46 : void Lock();
47 :
48 : // Unlocks the given mutex. The mutex is assumed to be locked and owned by
49 : // the calling thread on entrance.
50 : void Unlock();
51 :
52 : // Tries to lock the given mutex. Returns whether the mutex was
53 : // successfully locked.
54 : bool TryLock() WARN_UNUSED_RESULT;
55 :
56 : // The implementation-defined native handle type.
57 : #if V8_OS_POSIX
58 : typedef pthread_mutex_t NativeHandle;
59 : #elif V8_OS_WIN
60 : typedef CRITICAL_SECTION NativeHandle;
61 : #endif
62 :
63 : NativeHandle& native_handle() {
64 : return native_handle_;
65 : }
66 : const NativeHandle& native_handle() const {
67 : return native_handle_;
68 : }
69 :
70 : private:
71 : NativeHandle native_handle_;
72 : #ifdef DEBUG
73 : int level_;
74 : #endif
75 :
76 : V8_INLINE void AssertHeldAndUnmark() {
77 : #ifdef DEBUG
78 : DCHECK_EQ(1, level_);
79 : level_--;
80 : #endif
81 : }
82 :
83 : V8_INLINE void AssertUnheldAndMark() {
84 : #ifdef DEBUG
85 : DCHECK_EQ(0, level_);
86 : level_++;
87 : #endif
88 : }
89 :
90 : friend class ConditionVariable;
91 :
92 : DISALLOW_COPY_AND_ASSIGN(Mutex);
93 : };
94 :
95 :
96 : // POD Mutex initialized lazily (i.e. the first time Pointer() is called).
97 : // Usage:
98 : // static LazyMutex my_mutex = LAZY_MUTEX_INITIALIZER;
99 : //
100 : // void my_function() {
101 : // LockGuard<Mutex> guard(my_mutex.Pointer());
102 : // // Do something.
103 : // }
104 : //
105 : typedef LazyStaticInstance<Mutex, DefaultConstructTrait<Mutex>,
106 : ThreadSafeInitOnceTrait>::type LazyMutex;
107 :
108 : #define LAZY_MUTEX_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER
109 :
110 :
111 : // -----------------------------------------------------------------------------
112 : // RecursiveMutex
113 : //
114 : // This class is a synchronization primitive that can be used to protect shared
115 : // data from being simultaneously accessed by multiple threads. A recursive
116 : // mutex offers exclusive, recursive ownership semantics:
117 : // - A calling thread owns a recursive mutex for a period of time that starts
118 : // when it successfully calls either |Lock()| or |TryLock()|. During this
119 : // period, the thread may make additional calls to |Lock()| or |TryLock()|.
120 : // The period of ownership ends when the thread makes a matching number of
121 : // calls to |Unlock()|.
122 : // - When a thread owns a recursive mutex, all other threads will block (for
123 : // calls to |Lock()|) or receive a |false| return value (for |TryLock()|) if
124 : // they attempt to claim ownership of the recursive mutex.
125 : // - The maximum number of times that a recursive mutex may be locked is
126 : // unspecified, but after that number is reached, calls to |Lock()| will
127 : // probably abort the process and calls to |TryLock()| return false.
128 : // The behavior of a program is undefined if a recursive mutex is destroyed
129 : // while still owned by some thread. The RecursiveMutex class is non-copyable.
130 :
131 : class V8_BASE_EXPORT RecursiveMutex final {
132 : public:
133 : RecursiveMutex();
134 : ~RecursiveMutex();
135 :
136 : // Locks the mutex. If another thread has already locked the mutex, a call to
137 : // |Lock()| will block execution until the lock is acquired. A thread may call
138 : // |Lock()| on a recursive mutex repeatedly. Ownership will only be released
139 : // after the thread makes a matching number of calls to |Unlock()|.
140 : // The behavior is undefined if the mutex is not unlocked before being
141 : // destroyed, i.e. some thread still owns it.
142 : void Lock();
143 :
144 : // Unlocks the mutex if its level of ownership is 1 (there was exactly one
145 : // more call to |Lock()| than there were calls to unlock() made by this
146 : // thread), reduces the level of ownership by 1 otherwise. The mutex must be
147 : // locked by the current thread of execution, otherwise, the behavior is
148 : // undefined.
149 : void Unlock();
150 :
151 : // Tries to lock the given mutex. Returns whether the mutex was
152 : // successfully locked.
153 : bool TryLock() WARN_UNUSED_RESULT;
154 :
155 : // The implementation-defined native handle type.
156 : typedef Mutex::NativeHandle NativeHandle;
157 :
158 : NativeHandle& native_handle() {
159 : return native_handle_;
160 : }
161 : const NativeHandle& native_handle() const {
162 : return native_handle_;
163 : }
164 :
165 : private:
166 : NativeHandle native_handle_;
167 : #ifdef DEBUG
168 : int level_;
169 : #endif
170 :
171 : DISALLOW_COPY_AND_ASSIGN(RecursiveMutex);
172 : };
173 :
174 :
175 : // POD RecursiveMutex initialized lazily (i.e. the first time Pointer() is
176 : // called).
177 : // Usage:
178 : // static LazyRecursiveMutex my_mutex = LAZY_RECURSIVE_MUTEX_INITIALIZER;
179 : //
180 : // void my_function() {
181 : // LockGuard<RecursiveMutex> guard(my_mutex.Pointer());
182 : // // Do something.
183 : // }
184 : //
185 : typedef LazyStaticInstance<RecursiveMutex,
186 : DefaultConstructTrait<RecursiveMutex>,
187 : ThreadSafeInitOnceTrait>::type LazyRecursiveMutex;
188 :
189 : #define LAZY_RECURSIVE_MUTEX_INITIALIZER LAZY_STATIC_INSTANCE_INITIALIZER
190 :
191 :
192 : // -----------------------------------------------------------------------------
193 : // LockGuard
194 : //
195 : // This class is a mutex wrapper that provides a convenient RAII-style mechanism
196 : // for owning a mutex for the duration of a scoped block.
197 : // When a LockGuard object is created, it attempts to take ownership of the
198 : // mutex it is given. When control leaves the scope in which the LockGuard
199 : // object was created, the LockGuard is destructed and the mutex is released.
200 : // The LockGuard class is non-copyable.
201 :
202 : template <typename Mutex>
203 : class LockGuard final {
204 : public:
205 183391612 : explicit LockGuard(Mutex* mutex) : mutex_(mutex) { mutex_->Lock(); }
206 182677388 : ~LockGuard() { mutex_->Unlock(); }
207 :
208 : private:
209 : Mutex* mutex_;
210 :
211 : DISALLOW_COPY_AND_ASSIGN(LockGuard);
212 : };
213 :
214 : } // namespace base
215 : } // namespace v8
216 :
217 : #endif // V8_BASE_PLATFORM_MUTEX_H_
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